/*
* FLINT PARTICLE SYSTEM
* .....................
* 
* Author: Richard Lord
* Copyright (c) Richard Lord 2008-2011
* http://flintparticles.org/
* 
* Licence Agreement
* 
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
* 
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/

package org.flintparticles.common.utils;

import nme.display.DisplayObject;
import org.flintparticles.common.utils.DisplayObjectUtils;

/**
 * Utility methods for use with display objects.
 */
class DisplayObjectUtils 
{
	/**
	 * Converts a rotation in the coordinate system of a display object 
	 * to a global rotation relative to the stage.
	 * 
	 * @param obj The display object
	 * @param rotation The rotation
	 * 
	 * @return The rotation relative to the stage's coordinate system.
	 */
	public static function localToGlobalRotation( obj:DisplayObject, rotation:Float ):Float
	{
		var rot:Float = rotation + obj.rotation;
		var current:DisplayObject = obj.parent;
		while(  current != null && current != obj.stage )
		{
			rot += current.rotation;
			current = current.parent;
		}
		return rot;
	}

	/**
	 * Converts a global rotation in the coordinate system of the stage 
	 * to a local rotation in the coordinate system of a display object.
	 * 
	 * @param obj The display object
	 * @param rotation The rotation
	 * 
	 * @return The rotation relative to the display object's coordinate system.
	 */
	public static function globalToLocalRotation( obj:DisplayObject, rotation:Float ):Float
	{
		var rot:Float = rotation - obj.rotation;
		var current:DisplayObject = obj.parent;
		while( current != null && current != obj.stage )
		{
			rot -= current.rotation;
			current = current.parent;
		}
		return rot;
	}
}
